#include<bits/stdc++.h>
#define rep(i,s,n) for (int i = (int)(s); i < (int)(n); i++)
#define all(v) begin(v),end(v)
using namespace std;
using ll = long long;
bool chmin(auto &a, auto b){ return a > b ? a = b, 1 : 0; }
bool chmax(auto &a, auto b){ return a < b ? a = b, 1 : 0; }



int main(){
    cin.tie(0)->sync_with_stdio(0);

	int h, w, n; cin >> h >> w >> n;
	vector<int> a(n), b(n);

	vector ikeru(2*(h+w), vector<int>(0));
	
	rep(i,0,n) {
		cin >> a[i] >> b[i];
		a[i] -= 1;
		b[i] -= 1;
		ikeru[a[i]].push_back(b[i]+w);
		ikeru[b[i]+w].push_back(a[i]);
		ikeru[a[i]+h+w].push_back(b[i]+h+h+w);
		ikeru[b[i]+h+h+w].push_back(a[i]+h+w);
	}

	vector<ll> dp(h+1,-1e18);
	vector<ll> dp2(h+1,1e18);
	dp[0] = 0;
	dp2[0] = 0;
	
	vector<bool> seen(2*(h+w));
	int px = 0, py = 0;
	int ax = 0, ay = 0;

	auto dfs = [&](auto self, int i) -> void {
		if (0 <= i && i < h){
			px++;
			ax++;
		}
		if (h <= i && i < h + w){
			py++;
			ay++;
		}
		if (h + w <= i && i < h + w + h) {
			ax++;
		}
		if (h + w + h <= i && i < h + w + h + w){
			ay++;
		}
		seen[i] = true;
		seen[(i + h + w) % (2 * (h + w))] = true;
		for (int j: ikeru[i]){
			if (seen[j]) continue;
			self(self, j);
		}
	};

	rep(i,0,h+w){
		if (seen[i] || seen[i+h+w]) continue;
		px = 0;
		py = 0;
		ax = 0;
		ay = 0;
		dfs(dfs, i);
		vector<ll> ndp(h+1,-1e18);
		vector<ll> ndp2(h+1,1e18);
		rep(i,0,h+1){
			if (i+px <= h) {
				chmax(ndp[i+px], dp[i] + py);
				chmin(ndp2[i+px], dp2[i] + py);
			}
			if (i+ax-px <= h) {
				chmax(ndp[i+ax-px], dp[i] + ay-py);
				chmin(ndp2[i+ax-px], dp2[i] + ay-py);
			}
		}
		swap(dp, ndp);
		swap(dp2, ndp2);
	}

	ll ans = 1e18;
	rep(i,0,h+1){
		if (dp[i] >= 0){
			chmin(ans, (ll)(h - i) * (w - dp[i]) + (ll)i * dp[i]);
			chmin(ans, (ll)(h - i) * (w - dp2[i]) + (ll)i * dp2[i]);
		}
	}

	ans = h * w - ans;
	cout << ans << '\n';
}